Sometimes I do a command that requires a ton of calculations, such as intersecting faces on a high poly model, then I get the beach ball and have to restart the program. Anyways, it’d be cool if I could just press esc to stop a command that’s giving me the beach ball.

To be honest, restarting the program isn’t that time consuming, but it would definitely save time if the esc key could stop a non-responsive command.

That is actually a really good idea, but the only flaw this this, is that when the computer is calculating, it has to complete the steps already initiated before it can complete any other commands, so this would end up having a similar function to Cmd+z.

Yeah, that’s true. The undo process also takes time, but it could just stop the command and allow you to undo the partially completed command. Designing this command might be more trouble than its worth.

Sometimes I do a command that requires a ton of calculations, such as intersecting faces on a high poly model, then I get the beach ball and have to restart the program.

[Emphasis added by me] Why do you stop (kill) SketchUp and restart it under such circumstances? Do you think that SketchUp would complete the complex operation successfully, if you allowed the program to continue? Do you choose not to wait for the complex operation to complete, and instead prefer to kill SketchUp, possibly losing recent unsaved changes, and then restart it? That course of action seems harsh, unless the complex operation would take really significant elapsed time - say five minutes or more.